Speciation Analysis of Ag₂S and ZnS Nanoparticles at the ng/L Level in Environmental Waters by Cloud Point Extraction Coupled with LC-ICPMS

Abstract

Toxicity and transport of metal-based nanoparticles (M-NPs) in environmental waters strongly depend on their speciation. A detailed understanding of the composition and speciation of M-NPs is necessary in order to move this field forward. Unfortunately, there is a shortage of analytical methods for metal-sulfide nanoparticles (MS-NPs) in the environment. In this work, a cloud point extraction (CPE) method combined with liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (LC-ICPMS) is developed for sensitive determination of Ag 2 S-and ZnS-NPs. Under the condition of 0.15% (w/v) of Triton X-114 (TX-114), pH 5, 20 mM NaNO 3 , incubation temperature of 45 °C, and time of 15 min, MS-NPs and non-MS-NPs were extracted into the surfactant-rich phase. With the sequent addition of 10 mM bis(p-sulfonatophenyl)phenylphosphane dehydrate dipotassium (BSPP) aqueous solution (100 μL) into the CPE-obtained extract, the non-MS-NPs were selectively dissociated into their ionic counterparts while maintaining the original size and shape of Ag 2 S-and ZnS-NPs. Interestingly, the micelle-mediated behavior suddenly disappeared with the addition of BSPP. Thus, the extract can be injected to LC-ICPMS for speciation analysis of trace Ag 2 S-and ZnS-NPs. This method exhibited excellent reproducibility (relative standard deviations < 4.9%), high sensitivity with the respective detection limits of 8 ng/L for Ag 2 S-NPs and 15 ng/L for ZnS-NPs, enabling recoveries of 81.3−96.6% for Ag 2 S-NPs and 83.9−93.5% for ZnS-NPs when they were spiked into three environmental water samples. Due to its potential applicability to low concentrations of Ag 2 S-and ZnS-NPs, this method is particularly convenient for monitoring the transformations of AgNPs and ZnO-NPs in the environment.

Facile Cloud Point Extraction for the Separation and Determination of Phenolic Acids from Dandelion

“…Consequently, Triton X-114 is selected as the surfactant. There are many factors influencing the extraction efficiency of CPE, mainly including surfactant concentration, ratio of salt, pH value, temperature, and incubation time . In order to achieve the optimal operation conditions, it is necessary to investigate carefully the parameters of CPE.…”

Nanomicellar Extraction of Polyphenols—Methodology and Applications Review

“…The cloud point extraction, although was originally used only to determine inorganic compounds (metal ions), has found great application in the extraction of organic compounds (including impurities of organic origin) and biologically active substances, which are often ingredients in cosmetics or drugs. The latest application of the CPE technique also includes pro-environmental methods for the determination of nanoplastic [ 48 ] and nanometal [ 49 ] residues in the ecosystem, iron in beer [ 50 ], or the recycling of homogeneous catalysts from micellar solutions [ 51 ]. The CPE technique was successfully used to isolate active substances from plant and biological samples (blood, hair, urine, plasma, saliva) and also from food products.…”

Elemental Speciation Analysis in Environmental Studies: Latest Trends and Ecological Impact

“…In it, Triton X-114 was used as extractant, bis(p-sulfonatophenyl)phenylphosphane dehydrate dipotassium was used to dissolve interfering NPs, and EDTA was used to mask ionic species, with liquid chromatography coupled to ICP-MS used for separation and quantification. Overall, the method did not involve the use of harmful solvents or acids, making it a green alternative for analysis [120]. The same authors also developed a MSPE method to quantify Ag 2 S NPs and the remaining fraction of AgNPs in the same samples, by means of a treatment step with acetic acid that dissolved all AgNPs except Ag 2 S NPs [121].…”